Thread: Brake issue

A friend of mine who lives in California, has a ex-mil S2A 109 (Australian GS), he uses it infrequently, it has a brake issue.
He tells me that when it sits for sometime (read months) in between use, the brake pedal goes to the floor, he says he can bleed it with help and the pedal returns and the brakes work.
To my way of thinking if air is getting in, fluid must be getting out, but he hasn't mentioned anything about leaking brake fluids anywhere, also I'm unsure as to whether he has a VH booster, what are peoples thoughts, cheers Dennis

If hes not bleeding air out of the system Its the fill port seal OR the MC recirculating.

for the single brake line circuit the fill port seal is at the end of the spring as per the little seal indicated above the 15 in this pic



to check for recirculating in a dual system you might see unusual action in the reservoir one fluid level will drop and the other will drop a little then rise or only one side will lower.

while each dual Master cylinder is a little different essentially its the front seal on the secondary piston in this picture (its under the part labeled as the fluid level sensor) that will be causing the issue.



do not keep driving with this not working properly. they do not fix themselves they just fail spectacularly resulting in you rolling through your front gate.

If hes bleeding air then the fill ports may have gunk in them so the fluid cant get into the MC proper when the brakes are applied then released a low pressure is created inside the MC and air can be sucked in past the front seal.